Demand for electricity is at its peak during daytime in summer season. For coping with such an occasion, there is suggested an apparatus in a Japanese utility model laying-open gazette issued under No. 60-1543. This apparatus is designed such that a compressor consuming the largest amount of electricity in the apparatus is stopped on such occasion and cooling of rooms is carried out instead by cold which has been accumulated in a heat accumulator during a time other than the peak time.
However, in the case of the above-described apparatus, since the same compressor, condensor and decompressing mechanism are co-utilized both in the cold accumulating cycle and in the cooling cycle, there occur such problems as will be described next.
A switching operation between the cold accumulating cycle and the cooling cycle is carried out by means of switching valves provided in the respective cycles. However, since the decompressing mechanism is co-utilized in the two cycles, it is difficult to adjust the decompressing mechanism to provide its optimum performance for each of the cycles, thereby impairing the total performance of the air conditioning apparatus. More specifically, control operation for electric load variation is not carried out linearly, and the cooling temperature of the apparatus violently varies with a power-on or off of the compressor. Further, since there occurs a zoning phenomenon with each of the compressors, it is difficult to partition a space into a plurality of rooms such that each room may be most comfortably air-conditioned.
Moreover, since the conventional apparatus comprises an integral type incorporating both the indoor unit and the outdoor unit, it is costly and troublesome to install additional apparatuses. Also, because of the one-to-one correspondence between the indoor unit and the outdoor unit, if it is desired to install a plurality of indoor units, the same number of outdoor units need be installed as well, whereby there occurs a necessity of obtaining a large space for the installment of the outdoor units.
Being the integral type incorporating the indoor unit and the outdoor unit including the heat accumulator, the conventional apparatus inherently has only a small cold accumulating capacity. Due to this limited cold accumulating capacity, the cold accumulated out of the peak time is consumed in a short time period, and thus the apparatus is not capable of significantly contributing to the improvement of the aforementioned tight electricity demand situation. Furthermore, in a building having load characteristics of 24 hour air conditioning (cooling cycle), it is impossible to operate the apparatus for the cold accumulating cycle.
With a view toward apparatus maintenance, if the compressor fails, there is no means to back up the apparatus. Also, since the heat accumulating tank is disposed in the indoor unit, there is danger of water leakage, or if the apparatus is installed in a building, the great number of heat accumulating tanks makes the maintenance difficult.